199 research outputs found
Strange Nonchaotic Attractors in Harper Maps
We study the existence of Strange Nonchaotic Attractors (SNA) in the family
of Harper maps, proving that they are typical but not robust in this family.
Our approach is based on the theory of linear skewproducts and the spectral
theory of Schrodinger operators
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TR-2015-1 Preliminary Hydraulic Design of a Step-Pool-Type, Nature-Like Fishway March 30, 2015
This technical report presents a method for the preliminary hydraulic design of a step-pool type, nature-like fishway. The method and its companion example, “Nature-Like Fishway at the Obex Mills dam site”, are presented as an instructional exercise illustrating how one may bridge the gap between a conceptual layout and subsequent, more detailed, design phases. This report is intended to supplement the “Federal Interagency Nature-like Fish Passage Guidelines for Atlantic Coast Diadromous Fishes” (unpublished; forthcoming 2015)
Semi-analytical computation of heteroclinic connections between center manifolds with the parameterization method
This paper presents methodology for the computation of whole sets of
heteroclinic connections between iso-energetic slices of center manifolds of
center x center x saddle fixed points of autonomous Hamiltonian systems. It
involves: (a) computing Taylor expansions of the center-unstable and
center-stable manifolds of the departing and arriving fixed points through the
parameterization method, using a new style that uncouples the center part from
the hyperbolic one, thus making the fibered structure of the manifolds
explicit; (b) uniformly meshing iso-energetic slices of the center manifolds,
using a novel strategy that avoids numerical integration of the reduced
differential equations and makes an explicit 3D representation of these slices
as deformed solid ellipsoids; (c) matching the center-stable and
center-unstable manifolds of the departing and arriving points in a Poincar\'e
section. The methodology is applied to obtain the whole set of iso-energetic
heteroclinic connections from the center manifold of L2 to the center manifold
of L1 in the Earth-Moon circular, spatial Restricted Three-Body Problem, for
nine increasing energy levels that reach the appearance of Halo orbits in both
L1 and L2. Some comments are made on possible applications to space mission
design.Comment: 36 pages, 14 figure
Possible polarisation and spin dependent aspects of quantum gravity
We argue that quantum gravity theories that carry a Lie algebraic
modification of the Poincare' and Heisenberg algebras inevitably provide
inhomogeneities that may serve as seeds for cosmological structure formation.
Furthermore, in this class of theories one must expect a strong polarisation
and spin dependence of various quantum-gravity effects.Comment: Awarded an "honourable mention" in the 2007 Gravity Research
Foundation Essay Competitio
El miedo a lo desconocido en "El almohadón de plumas", de Horacio Quiroga, y "El huésped", de Amparo Dávila: un enfoque comparatístico
La tematología es un método que utiliza la Literatura Comparada para analizar dos obras a partir del tema del que hablan. Cada uno de estos temas se construye a partir de unidades más pequeñas, llamadas motivos. Cuando los motivos se modifican ocurre un desplazamiento temático, lo que origina una actualización del tema en una determinada obra.
Tanto “El almohadón de plumas”, de Horacio Quiroga, como “El huésped”, de Amparo Dávila, están construidos a partir del mismo tema: el miedo a lo desconocido. Sin embargo, cada actualización es diferente, lo que puede apreciarse gracias a la modificación de cuatro motivos: la focalización del narrador, la triada trágica, la nominalización de los antagonistas y los desdoblamientos
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TR-2013-1 Fishway Inspection Guidelines (6/5/2013)
This technical report provides guidance for engineers, biologists, operators, regulators and dam owners involved in the inspection of fishways at dams. Volitional fish ladders, fish lifts, and other fish passage and protection facilities are devices of varying complexity frequently integrated into sophisticated reservoir management and hydropower installations. As with any device, maintenance of fish passage facilities is necessary to ensure their proper operation. Improper operation of fishways may limit or eliminate entire year classes of diadromousfish. Routine fishway inspections are a critical component of an overall fish passage operation and maintenance plan
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